Wide gamut tunable led elements with less undesired color artifacts and display systems and methods thereof

Abstract

A color adjustable LED system configured to emit light of a plurality of peak wavelengths in response to a change in driving current density includes an n-type region, a p-type region, and a multiple quantum well (MQW) region formed between the n-type region and the p-type region. The MQW region includes parallel layers each alloyed with a percentage of indium to achieve a light emission range between 400 nm and 600 nm, and one or more shaped recesses formed within a portion of the parallel layers. Each of the one or more shaped recesses has a lower concentration of the alloyed percentage of indium than other portions of the parallel layer. A transition region between the one or more shaped recesses and the other portion of the parallel layer has a higher concentration of an alloyed percentage of the indium, the alloyed percentage of the indium decreasing with a distance from the one or more shaped recesses. The use of a monolithic color adjustable LED system may utilize a single LED as a pixel.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 438,435, filed January 11, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This technology relates to color-tunable light-emitting diodes, LED systems including such light-emitting diodes, LED display systems, and methods thereof. Background Technology

[0004] For a wide range of applications, including near-eye displays and larger form factor displays viewed at a distance, displays based on inorganic light-emitting diodes (LEDs), specifically smaller mini-LEDs and μ-LEDs, are seen by the display industry as emerging successors to those displays, including organic light-emitting diodes (OLEDs). They offer numerous advantages, including high efficiency, environmental durability, greater scaling, and higher brightness.

[0005] However, the development of improved inorganic LEDs and LED displays has been hampered by problems associated with integrating separately manufactured red, green, and blue LEDs into functional and controllable LED systems capable of emitting light across the visible spectrum. Each LED comprises a layer of electron-rich n-type regions, aperture-rich p-type regions, and multiple quantum well (MQW) regions between the n-type and p-type regions. The MQW regions consist of multiple individual quantum wells with smaller band gaps due to alloying, which are positioned between higher band gap materials. The smaller band gap quantum wells confine electrons and apertures to facilitate recombination and corresponding light emission.

[0006] As an example, blue and green LEDs are often based on III-N material systems. Indium is alloyed with GaN in varying amounts to reduce the band gap of the quantum well. Where blue light can be generated using quantum wells containing ~10% indium, the addition of indium results in longer wavelength emission, such as green. Obtaining blue, green, and red using only III-N material systems is limited due to the difficulty in incorporating the high levels of indium utilized for red. Strain and solubility issues arise with increasing indium concentration. Conventionally, red emitters are used as an alternative, utilizing III-V material systems with AlInGaP. Relying on these disjointed material systems, associated separately with blue and green, and red alone, typically requires the separate fabrication of each material system before integration with silicon-based control electronics in the display. This integration generally leads to higher costs and more complex manufacturing processes.

[0007] To avoid the need for separate LED growth, three main approaches have emerged to develop more efficient InGaN LEDs with tunable red and overall visible light emission, reducing the aforementioned integration issues: europium doping, the use of porous GaN substrates, or nanowire growth. However, each of these approaches suffers from the challenges of complex display fabrication and compromised emission uniformity.

[0008] Furthermore, a key challenge facing such displays is that conventionally, these light-emitting diodes (LEDs) only provide emission of a single, fixed color. Therefore, it is typical in the prior art to transfer a set of LEDs of various colors (usually essentially red, green, and blue). This then employs more than one emitter to provide full-color reproduction, but this comes with increased manufacturing and electronic drive complexity and cost. This can be overcome using novel color-tunable LEDs to provide full-color reproduction and image reconstruction with only one LED per pixel when constructed and operated in the manner disclosed herein. Summary of the Invention

[0009] Examples of this technology relate to color-tunable LEDs, LED systems, and display systems that are essentially monolithic due to the use of common single-crystal material systems, configured to emit light with multiple peak wavelengths in response to variations in drive current density. Both LEDs and LED systems are ideally fabricated using common GaN processing techniques with single-crystal GaN material systems (also referred to as monolithic systems in the examples herein). A single crystal is defined herein as an ordered arrangement of atoms forming a single wurtzite crystal. LEDs and LED systems include an n-type region, a p-type region with an optional electron blocking layer (EBL), and a multiple quantum well (MQW) region formed between the n-type and p-type regions. The MQW region comprises parallel layers, each alloyed with a certain percentage of indium to achieve a light emission range between 400 nm and 600 nm. The MQW region is formed on a first active doped layer or region, which is selectively patterned along a surface with recesses having one or more shapes and one or more spacing configurations to facilitate controlled color emission in the MQW layer of the MQW region. Each of one or more portions of the MQW layer in the MQW region that conforms to the recesses in the first active doped layer has a lower concentration of alloyed indium percentage compared to other portions of the MQW layer in the MQW region. The transition region located between the region conforming to the recesses in the first active doped layer and other portions of the MQW layer has a higher concentration of alloyed indium percentage compared to the region conforming to the recesses in the first active layer, the alloyed indium percentage decreasing with distance from one or more such recesses.

[0010] A method for fabricating a color-tunable LED system configured to emit light with multiple peak wavelengths in response to variations in drive current density, the method comprising forming a first actively doped n-type or p-type layer. In various examples, this first actively doped n-type or p-type layer may be etched or otherwise patterned to produce multiple recesses of various shapes, sizes, sidewall angles, or other characteristics and spacing configurations as mentioned elsewhere herein. MQW regions are grown on the first actively doped n-type or p-type layer. The MQW regions comprise parallel layers, each alloyed with a certain percentage of indium to achieve a light emission range between 400 nm and 600 nm, wherein the layers of the MQW regions are adapted to one or more of the shaped recesses formed within the first actively doped layer. The portions of the parallel layers adapted to the recesses patterned in the first actively doped layer have a lower concentration of the alloyed percentage of indium compared to other portions of the parallel layers. The transition region between the portion of the parallel layer that conforms to the recess in the first active layer and the rest of the parallel layer has a higher concentration of alloyed indium, the alloyed percentage of which decreases with distance from the portion of the parallel layer that conforms to the recess. A second active doped layer is grown on the MQW region, the second active doped layer having the opposite charge to the first active layer.

[0011] In examples utilizing this technology, each color-tunable LED can act as a pixel element, and each such LED is capable of rapidly switching between two or more emission wavelengths in response to a corresponding rapid change in drive current density, allowing the eye to perceive a single color. Individual pixel elements can be arranged multiple times to produce a full display system of any desired shape or resolution. Multiple color-tunable LEDs can be combined and arranged to form a complete, optionally monolithic LED display system. In other examples utilizing this technology, the functional pixel element may optionally include more than one monolithic color-tunable LED, each monolithic color-tunable LED having recesses of the same or different densities or designs patterned in a first active doped layer and capable of emitting visible light in multiple colors or a fixed color.

[0012] In other examples, color-tunable LEDs may be supplemented with additional components to form the basis of pixel elements. These additional components may take the form of device elements, such as transistors, capacitors, and diodes. The device elements, together with the color-tunable LEDs, may be electrically connected to form various circuits, such as current sources and active matrix circuits for each pixel element. Pixel elements function by rapidly switching between two or more emission wavelengths in response to a corresponding rapid change in drive current density, allowing the eye to perceive a single color. Individual pixel elements can be arranged multiple times to produce a full-color-tunable LED display system of any desired shape or resolution.

[0013] In an example where color-tunable LEDs are included in the pixel elements, additional circuitry can be integrated to feed voltage and current signals to drive the LED array, together forming an LED display system. This circuitry can be in the form of an external chip, or it can be integrated with the LEDs on a chip to create an optionally monolithic LED display system.

[0014] As described and claimed herein, color-tunable LEDs and color-tunable LED display systems offer numerous advantages and can be effectively used in many different applications, such as microdisplays and larger format displays, commercial lighting, light-based data communications, and more. In particular, examples of this technology provide color-tunable LEDs that emit light across the visible spectrum without requiring any additional color converters. This reduces complexity for many applications, provides better performance, and lowers costs. For some examples herein, monolithic is defined as a common InGaN / GaN, III-N material system used only within the same wafer. Variations of examples of this technology further enable monolithic color-tunable LEDs without Eu doping, the use of porous GaN substrates, or nanowire growth. Furthermore, in other examples, a single LED can be configured to act as a pixel, instead of using three LEDs to selectively emit red, green, and blue light, as is the common RGB approach widely used today. Reducing the number of LED subpixels used to form a pixel increases potential display resolution and reduces the footprint. This smaller footprint is particularly advantageous in μ-LED displays intended for near-eye applications such as virtual reality or extended reality. It also reduces costs and enables more efficient manufacturing.

[0015] Furthermore, the problems discussed in the background art can be solved by using alternative methods to achieve simpler systems, in some examples using monolithic (i.e., common and general) single-crystal material systems (such as single-crystal GaN) in the fabrication of LED components / systems. Monolithic is defined herein as a common InGaN / GaN, III-N material system used solely for the growth of all semiconductors on the same wafer. III-N is defined herein as a category of materials including GaN and elements alloyed with GaN such as indium or aluminum.

[0016] In other alternative implementations, emission-driven schemes are described that can be used to improve and / or reduce certain undesirable visual artifacts (such as color splitting, etc.).

[0017] In other alternative implementations, the design and fabrication of the LED element / system can incorporate the modulation of the quantum well to further optimize light emission. To cite just one example, the quantum well can be independently configured to emit a wider range of green and blue light—in order to achieve wide color gamut displays, as discussed further below. Attached Figure Description

[0018] Figure 1A This is a cross-sectional image of an example of a patterned recess formed along one surface of the first active doped layer (an n-type material in this example) before the final layer is formed;

[0019] Figure 1B yes Figure 1A An aerial view of a section showing recesses of varying shapes patterned along a surface of the first active doped layer (an n-type material in this example), with edges shown and represented by dashed lines. Figure 1A The cross-section;

[0020] Figure 1C yes Figure 1B A cross-sectional image of an example color-tunable LED system, which incorporates a first active doped layer (in the example, an n-type material) patterned along a surface with recesses having multiple shapes and spacings, the recesses promoting controlled color emission in the MQW layer of the LED's MQW region;

[0021] Figure 2 A graph from CIE 1931 is shown, depicting a wider color gamut, such as that of an LED display made by independently optimizing a single quantum well.

[0022] Figure 3 This is a graph illustrating how a single-color tunable LED can be driven at different current densities by changing the duty cycle and current to produce different colors of equal intensity.

[0023] Figure 4A and Figure 4B The graph shows an example of a single-color tunable LED being driven to produce the purple color perceived by the eye by rapidly alternating between pulse current densities that generate red wavelength emission and blue wavelength emission.

[0024] Figure 5A and Figure 5B The graph shows an example of a single-color tunable LED being driven to produce white light as perceived by the eye by rapidly alternating between pulsed current densities that produce yellow wavelength emission and blue wavelength emission.

[0025] Figure 6A A top view of an array of light-emitting diode elements, which may be made and / or manufactured as in any of the displays described herein, is shown.

[0026] Figure 6B The spatial dithering mode for emitting two colors is shown. Figure 5A An array of light-emitting diode elements;

[0027] Figure 6C This demonstrates a spatial dithering pattern that emits two colors, with... Figure 5B An array of light-emitting diode elements with opposite assignments is shown;

[0028] Figure 7 This is a graph illustrating how a single-color tunable LED can be driven at different current densities by changing the duty cycle and current to produce different colors of equal intensity.

[0029] Figure 8A The example of a single-color tunable LED being driven to produce a single color perceived by the eye by rapidly alternating between pulse current densities that generate metamerism wavelengths is shown in a graph of the CIE 1931 color space.

[0030] Figure 8B It is a graph showing the CIE 1931 color space, which can reproduce color lines using metamer pairs with equal brightness;

[0031] Figure 8C It is a graph showing the color gamut of a display system using an array of color-tunable μ-LEDs and combined with an array of fixed-color μ-LEDs in the CEI 1931 color space.

[0032] Figure 9A This is the top-level block diagram of the micro LED display system;

[0033] Figure 9B This is a diagram of a micro-LED pixel element with current and pulse width modulation control;

[0034] Figure 9C This is a diagram of the metamer selection block;

[0035] Figure 10 An array of light-emitting diode elements is shown;

[0036] Figure 11 This is the top-level block diagram of the micro LED display system;

[0037] Figure 12 An array of light-emitting diode elements is shown;

[0038] Figure 13 This is the top-level block diagram of the micro LED display system; Detailed Implementation

[0039] like Figure 1A , Figure 1B and Figure 1CThe examples illustrated by color-tunable LED technology offer several advantages, including providing color-tunable LED systems that can be effectively used in a number of different applications (such as displays, commercial lighting, communications, etc.) and can optionally be made using a single material system.

[0040] For more specific reference Figure 1A In this example, in order to produce a color-tunable LED system 10 (1), a patterned first doped active layer including an n-GaN layer is formed on an initial growth substrate 25 (in an exemplary manner, such as silicon or sapphire), but other types and / or numbers of doped layers and / or substrates may be used. In this example, the surface of the first active layer 12 is patterned with shaped recesses 18(1a), 18(1b), and 18(1c), such as the outer periphery or cross-sectional shape of an arrangement including circles, triangles, squares, pentagons, hexagons, or multiple such shapes, wherein the diameter of the top surface is from about 150 nm to about 10 μm, the spacing between the recesses 18(1a), 18(1b), and 18(1c) is from about 150 nm to about 10 μm, and the height difference or depth difference from the surface of the recesses 18(1a), 18(1b), and 18(1c) is less than about 5 μm, in order to achieve color-tunable emission in the MQW region, but other patterns with other sizes, spacing, and / or shapes may be used. The sidewalls of recesses 18(1a), 18(1b), and 18(1c) may be at an angle between 0 and 90 degrees relative to the substrate in some examples, and between 90 and 180 degrees in other examples. The sidewalls of recesses 18(1a), 18(1b), and 18(1c) may have positively tilted, negatively tilted, or vertically tilted sidewalls relative to the growth substrate 25. Recesses 18(1a), 18(1b), and 18(1c) are added to control the indium content and thus the emission spectrum from the LED, due to differences in indium incorporation along different crystal planes. These recesses 18(1a), 18(1b), and 18(1c) locally relax the crystal structure, thereby modifying indium absorption in the MQW region. The use of a shaped recess 18(1c) at a 90-degree angle relative to the substrate is expected to enhance short-wavelength blue emission from the color-tunable LED system 10(1). The use of positively tilted shaped recesses 18(1a), 18(1b), or negatively tilted shaped recesses at angles less than or greater than 90 degrees relative to the substrate can promote longer-wavelength red emission from the color-tunable LED system 10(1). The selective incorporation of different shaped recesses 18(1a), 18(1b), and 18(1c) can be used to control the color emission from the color-tunable LED system 10(1) at a fixed current density.

[0041] Figure 1A The geometry and layout of the recesses 18(1a), 18(1b), and 18(1c) shown can be formed by common semiconductor process steps, such as epitaxial overgrowth, dry etching, or wet etching. These process steps are performed on a first doped active layer 12, which is the first electrically active layer in the device. The formation of the recesses 18(1a), 18(1b), and 18(1c) is performed prior to the formation of the MQW region 16. The density and size of these selectively formed recesses 18(1a), 18(1b), and 18(1c) can be advantageously tuned to modify the indium content to obtain a desired color emission spectrum from the LED.

[0042] The recesses 18(1a), 18(1b), and 18(1c) can be arranged in an array, such as a regular or hexagonal array, as exemplified. Figure 1B As shown. One or more of the same or different shaped recesses 18(1a), 18(1b), and 18(1c) can be incorporated into a single LED. The recesses 18(1a), 18(1b), and 18(1c) can take the shape of a circle, triangle, square, pentagon, hexagon, or an arrangement of multiple such shapes.

[0043] After creating the recesses 18(1a), 18(1b), and 18(1c), surface treatments can be performed to clean and remove any potential surface damage. These surface treatments can take the form of a combination of dry etching and wet etching or cleaning.

[0044] refer to Figure 1C The MQW region 16 is formed on the first doped active layer 12 and, in this example, includes a parallel GaN layer alloyed with a certain percentage of indium to achieve an optical emission range between 400 nm and 600 nm. By way of example, a representative percentage of indium could be 18%. The regions of the parallel layer of the MQW region 16 conforming to the underlying recesses 18(1a), 18(1b), and 18(1c) have a lower concentration of the alloyed percentage of indium compared to the regions of the parallel layer of the MQW region 16 not conforming to the recesses 18(1a), 18(1b), and 18(1c). These other regions of the parallel layer of the MQW region 16 not conforming to the recesses 18(1a), 18(1b), and 18(1c) are also referred to herein as planar MQWs. Additionally, in this example, Figure 1CThe transition region 22 between the portion of the parallel layer that conforms to the recesses 18(1a), 18(1b), and 18(1c) and the other regions of the parallel layer that are not in the recesses 18(1a), 18(1b), and 18(1c) has a higher concentration of alloyed percentage of indium, the alloyed percentage of indium decreasing in other regions of the parallel MQW layer with increasing distance from the recesses 18(1a), 18(1b), and 18(1c).

[0045] The sides of recesses 18(1a), 18(1b), and 18(1c) can be surfaces of semi-polar or non-polar crystal planes, which contain less indium due to differences in the indium adhesion coefficient during growth. The semi-polar or non-polar MQWs of the parallel layers of MQW region 16 located in recesses 18(1a), 18(1b), and 18(1c) are also thinner than the planar MQWs or other portions of the parallel layers of MQW region 16. The reduction of indium in the portions of MQW region 16 that conform to the parallel layers of recesses 18(1a), 18(1b), and 18(1c) relative to the designed planar MQW 16 is accompanied by the formation of indium-rich "transition regions" or transition regions 22 in the MQWs of MQW region 16 adjacent to recesses 18(1a), 18(1b), and 18(1c). The indium concentration is highest at the periphery of recesses 18(1a), 18(1b), and 18(1c), and decreases with distance from recesses 18(1a), 18(1b), and 18(1c) to the indium level initially incorporated into the designed planar MQW.

[0046] In this example, although the indium-depleted semi-polar or non-polar MQWs of MQW region 16 may have 5%-15% indium content within recesses 18(1a), 18(1b), and 18(1c), the planar MQWs of MQW region 16 have an indium concentration as high as 30%-50% in each of the transition regions 22 closest to recesses 18(1a), 18(1b), and 18(1c). The concentration in other portions of the parallel layers of MQW region 18 decreases to the designed 18% indium as the distance from recesses 18(1a), 18(1b), and 18(1c) increases. Similar to the case of intentionally high indium content growth in continuous planar MQWs, this localized increase in indium does not impair electron-pore recombination efficiency because these locally increased regions are strain-relaxed due to recesses 18(1a), 18(1b), and 18(1c).

[0047] A second active doped layer of opposite charge type is formed on MQW region 16. In this example, the second active doped layer is a p-type AlGaN EBL layer 20 having a p-type GaN layer 14, but in some examples other types and / or numbers of layers may be used and the EBL layer is optional. The EBL layer 20 is a p-type AlGaN layer and is located on the portions of the parallel layer conforming to all the shaped recesses 18(1a), 18(1b), and 18(1c) and on the other regions of the parallel layer outside the shaped recesses 18(1a), 18(1b), and 18(1c). The p-type EBL layer 20 is referred to in more detail below by way of example. Figure 1C The layer can be a p-AlGaN layer containing 5% aluminum, but other types and / or numbers of electron blocking layers can be used. A p-type GaN layer 14 is then formed on the p-type EBL layer 20, but other types and / or numbers of layers can be formed. When the p-type GaN layer 14 is grown at a higher temperature on top, the higher surface mobility results in the filling of recesses 18(1a), 18(1b), and 18(1c), such as... Figure 1C The example in the text is shown.

[0048] In the final structure, the shaped recesses 18(1a), 18(1b), and 18(1c) are adjacent to and located between the two oppositely charged regions, namely the first doped active layer 12 and the second active layer 14, and the recombination of these charges occurs in the InGaN layer of the MQW region 16 to generate light. The recesses 18(1a), 18(1b), and 18(1c) facilitate easy charge injection into the InGaN layer of the MQW region 16, especially at low currents. This is achieved by modifying the indium content in each indium gallium nitride (InGaN) layer in or around the MQW region 16 within or around each recess 18(1a), 18(1b), and 18(1c). Charge preferentially recombines initially in the indium-rich regions, resulting in longer wavelength emission.

[0049] Once the layer structure of the color-tunable LED system 10(1) has been grown, the LED or other optoelectronic device can be manufactured, for example, in a conventional manner. For LED formation, specific areas can be patterned using, for example, photolithography, where a photoresist acts as a mask. Dry etching can then be used to selectively remove the p-type layer 14, EBL layer 20, and MQW region 16, where no photoresist is present, to then approach the first active layer 12 of the n-type GaN. The etching process forms a single LED structure. Additionally, a top metal or other conductor (not shown) can be deposited on the p-type GaN layer 14 to form the anode. Subsequently, another metal layer or other conductor (not shown) is deposited on the n-type GaN layer 12, which can be used as the cathode.

[0050] Color-tunable LEDs and LED systems fabricated according to examples of this technology, optionally using common single-crystal material systems (also known as monoliths), produce a desired color emission range from ~640 nm to ~425 nm across the visible spectrum. Figure 1C The illustrated color-tunable LED system is an example of this technology. In this example, a low current density applied to the color-tunable LED system 10(1) produces red emission. As the current density increases, the emission shifts significantly to blue. This causes the color to change from red to orange, yellow, green, and then blue. For smaller LEDs, the color emission change uses a lower current than for larger LEDs because smaller LEDs would have a higher current density at the same applied current as larger LEDs. By way of example, for a 35 μm color-tunable LED, the current density ranges from ~6 x 10⁻⁵ to ~8 x 10⁻² mA / μm² for red and blue, respectively.

[0051] The emission range of color-tunable LEDs and LED systems described herein can be tuned to emit longer or shorter wavelengths depending on the percentage of planar indium utilized. An increased percentage of indium in the planar MQW of MQW region 16 (e.g., from 18% to 25%) increases the inclusion of indium in the semi-polar or non-polar MQW of the portion of MQW region 16 in recesses 18(1a), 18(1b), and 18(1c), as well as the local indium composition in the planar MQW adjacent to recesses 18(1a), 18(1b), and 18(1c). This will enable a shift to longer wavelengths from the total optical wavelength range generated in one of the color-tunable LED systems 10(1) at both low and high current densities. Conversely, if the designed planar MQW indium percentage of MQW region 16 is reduced (e.g., from 18% to 15%), the incorporated recesses 18(1a), 18(1b), 18(1c), and transition region 22, having the same density, will shift the generated wavelength range to shorter values ​​under both low and high current densities. In the case of less indium incorporated into the semi-polar or non-polar MQW of the portions of MQW region 16 in recesses 18(1a), 18(1b), and 18(1c), the corresponding indium-rich region of transition region 22 of MQW region 16 also contains less indium.

[0052] In addition to designing essentially three regions with defined percentages of indium, it may be desirable to modify some of the MQW layers with different percentages of indium, thereby effectively creating four or more regions tuned to emission at a desired wavelength, thus influencing the curve of the reproducible color range emitted by the LED as a function of current density. For example, in one embodiment, reducing the indium in the deeper, lower layers of the horizontal MQW layer can shift the emitted color curve 301 toward emerald green (e.g., ...). Figure 2 (as shown), thereby expanding the color gamut.

[0053] In addition to engineering the geometry and number of the shaped recesses 18(1a), 18(1b), and 18(1c) included in each color-tunable LED system 10(1) to modify light emission, other techniques exist that can be used in conjunction with or independently of them. For example, each individual quantum well in the MQW region 16 can be designed to have a unique indium concentration. The unique indium concentration in each quantum well in the MQW region 16 will modify light emission. Generally, for conventional LEDs, the quantum wells in the MQW region 16 located closest to the second doped region 14 will dominate light emission at low applied current densities, while the quantum wells located closer to the first doped region 12 will only contribute at high current densities.

[0054] Although the shaped recesses 18(1a), 18(1b), and 18(1c) interrupt the planar MQW region 16 in the color-tunable LED system 10(1), the semi-polar or non-polar MQWs of the parallel layers of the MQW region 16 in the recesses 18(1a), 18(1b), and 18(1c) are thinner and have a lower indium concentration, while the transition region 22 is formed in the MQWs of the MQW region 16 adjacent to the shaped recesses 18(1a), 18(1b), and 18(1c) and has an increased indium concentration. At low applied current densities, carrier injection is dominated by lateral injection from the shaped recesses 18(1a), 18(1b), and 18(1c) into the transition region 22, which has a higher indium content. As the applied bias voltage and corresponding current density increase, the generated light dominates by being vertically injected into the planar MQW 16, away from the shaped recesses 18(1a), 18(1b), 18(1c), and the transition region, to produce light with shorter wavelengths. At even higher current densities, the bandgap bends further, and the filling of excited states in the quantum wells and the filling of the MQW 16 conforming to the shaped recesses 18(1a), 18(1b), and 18(1c) occur to produce even shorter wavelengths of emission. Based on the current injection method, the indium content in each MQW of the engineered MQW region 16 can be very useful for engineering the emission range, especially at medium or high injection currents. Due to the lateral current injection mechanism, emission at low current densities will have a weaker dependence on the vertical distance of each quantum well in the MQW region 16.

[0055] The indium content of each MQW in tuned MQW region 16 can be advantageously applied to better engineer green and blue emission, thereby enhancing and / or widening the coverage of the observable color space, such as Figure 2 As shown. In an exemplary embodiment, the quantum well closest to the second doped region 14 will retain a nominal amount of indium, such that region 22, which is close to the transition of shaped recesses 18(1a), 18(1b), and 18(1c), produces a desiredly increased indium concentration for the selected long emission wavelength. Quantum wells in the MQW region 16 located further from the second doped region 14 will have an amount of indium that is between 1% and 15% lower than that of the quantum well closest to the second doped region 14. Quantum wells further from the second doped region 14 with a lower amount of indium will promote shorter wavelength emission, such as green and then blue, because vertical current injection dominates at higher current densities.

[0056] It should be understood that Figure 2 The wide color gamut can be applied to any and / or all of the color gamuts discussed in this paper. Specifically, Figures 4 and 5... Figures 8A to 8CThe color gamut can be widened (e.g., in the green and / or blue regions) according to the methods, techniques and systems discussed herein to produce this display.

[0057] Applying independent optimizations to the quantum wells in MQW region 16 to engineer a larger blue emission will increase the parabolic coverage of the color gamut from the unoptimized coverage 300 to the increased optimized coverage 301 in the green and blue spaces.

[0058] The color-tunable LED system 10(1) using a separately optimized quantum well in the MQW region 16 can be similarly formed by selective region growth or selective etching, followed by surface treatment and regrowth of the MQW region 16 and the second doped region 14. Alternatively, a strain-engineered buffer layer beneath the MQW region 16 can be engineered such that V-grooves or V-pit forming recesses 18(1a) nucleate on existing through dislocations and are formed during the growth of the MQW region 16.

[0059] In operations such as Figure 1C In one method of an LED in one of the exemplary tunable LED systems illustrated, a positive bias is applied to the anode while the cathode remains grounded. Alternatively, the cathode may be held negatively biased relative to a grounded p-type contact. This application of bias injects an aperture from the p-type GaN layer region 14 into the MQW in the MQW region 16 to recombine with electrons and generate light. However, before this occurs, the aperture must first overcome the energy barrier provided in some examples by an optional EBL (electron blocking layer) 20. The use of EBL 20 between the p-type GaN layer 14 and the MQW region 16 creates a large barrier for electrons while creating a smaller barrier for the aperture. The semi-polar or non-polar planes of the recesses 18(1a), 18(1b), and 18(1c) in one of the exemplary engineered tunable LED systems 10(1) have reduced internal piezoelectric fields, which reduce the barrier to the aperture provided by EBL 20. Therefore, the aperture (h+) can be more easily injected laterally rather than vertically into the indium-rich MQW to produce longer wavelengths, such as the emission color red. As the current density increases further, the aperture can be injected vertically, filling the planar MQWs away from each recess 18(1a), recess 18(1b), and recess 18(1c), thus producing shorter wavelength colors such as green. Increasing the current density further results in a continuous band bending, which, combined with the aperture clusters of the thin MQWs in each recess 18(1a), recess 18(1b), and recess 18(1c), produces even shorter wavelengths of light, such as blue. Through these mechanisms, current-driven, color-tunable emission is achieved.

[0060] The color tunability of the color-tunable LED system 10(1) can be advantageously achieved by using a pulsed current driving scheme through current control. Control of the duty cycle and current level of the applied current provides brightness control for each monolithic color-tunable LED system 10(1). To produce equal color brightness, red will have the highest duty cycle at low current density. Blue, operating at high current density, will have the lowest duty cycle. Intermediate colors will operate at current and duty cycles that are boundaries between red and blue. The driving differences for equal brightness among red, blue, and green are... Figure 3 The diagram is presented graphically, but not to scale. Tuning the duty cycle and current density for each wavelength makes the perceived intensity appear the same for each color, as the eye or detector integrates within the said period. The current applied during a given period can take many forms, including but not limited to square waves, sine waves, or ramps.

[0061] By utilizing the tuned duty cycle and current density of each desired emission wavelength / color, observed full-color emission from the color-tunable LEDs in the LED system 10(1) and the LED display system pixel can be achieved. Conventionally, three LEDs are used to form a pixel, with each LED emitting red, green, or blue. Uniquely achieved by color-tunable LEDs made according to examples of this technology, the number of individual LEDs used for a pixel can be reduced to as few as one. One or more color-tunable LED systems 10(1) can be driven such that multiple pulse wavelengths are emitted in each cycle of the duty cycle to allow the eye to perceive a single observed color. Examples of this method may include emitting red and blue during a single cycle to emit purple or pink due to the nature of color mixing. Figure 4A and Figure 4B The color gamut 400 represents the range of a single emission wavelength / color. The current density durations of red (401) and blue (402) control the weight of each wavelength to determine the color emitted during said period (403). A blue current density duration longer than the current duration used to balance the red intensity will emit violet. A red current density duration longer than the current duration used to balance the blue intensity will emit pink. A similar principle can be used between green and red wavelengths to emit yellow / orange hues, or between blue and green wavelengths to obtain cyan hues. The mixing of blue (402) wavelengths and yellow (405) wavelengths can be used, as in conventional lighting, to produce emitted white light (406) as seen by the observer, such as... Figure 5A and Figure 5BAs illustrated, the color-tunable LED system 10(1) allows wavelength mixing within a single cycle to produce different colors, thus enabling a single LED to be used as a pixel. Instead of fixed operating points for red, green, and blue, the color tunability of the color-tunable LED system 10(1) allows any color to be produced using rapidly varying current within a single cycle. This enables a single LED to act as a single full-color pixel element.

[0062] The color-tunable LED system 10(1) acting as a single pixel element can be implemented in various display architectures. By way of example, a passive matrix can be formed in which pixel elements are arranged together to constitute a display system. Furthermore, the color-tunable LED system 10(1) may include additional device elements to form the basis of the pixel elements. An example of such additional device elements is a transistor integrated with the color-tunable LED system 10(1) to form the basis of the pixel elements, but many other device elements, such as additional transistors, resistors, and capacitors, may also be integrated. These pixel elements, including device elements, can be similarly arranged to form an LED display system, such as device elements including transistors electrically connected to the LED to control its operating state (including switching, brightness, etc.). If the transistors or other device elements connected to the LED in the LED display system use the same material system as the LED, then these examples of display systems include common monocrystalline or monolithic color-tunable LED display systems. The pixel elements arranged to form the display system may also be integrated with additional circuitry such as a drive circuitry system, by way of example, to supply voltage and current to the array. This additional driving circuit system can take the form of an external chip and circuit, or it can take the form of a circuit system that is monolithically integrated with color-tunable LEDs into a common single-crystal material.

[0063] Therefore, as illustrated and described by the examples herein, examples of this technology provide color-tunable, optionally common, single-crystal or monolithic LED systems and LED display systems that can be effectively used in many different applications, such as displays, commercial lighting, communications, etc. In particular, examples of this technology provide the integration of color-tunable LEDs without the need for a color converter. This capability reduces the complexity of LED systems and provides better performance for increased brightness and efficiency. Examples of this technology enable the provision of color-tunable LEDs without Eu doping, using porous GaN substrates, or nanowire growth.

[0064] As exemplified in the embodiments described herein, each color-tunable LED can act as a pixel element, and each such LED is capable of rapidly switching between two or more emission wavelengths in response to a corresponding rapid change in drive current density, allowing the eye to perceive a single color. Individual light-emitting diode pixel elements can be arranged multiple times to produce a full display system of any desired shape or resolution, such as... Figure 6A As shown. Multiple color-tunable LEDs can be combined and arranged to form a complete optional monolithic LED display system. In other examples utilizing this technology, the functional pixel element may optionally include more than one monolithic color-tunable LED, each monolithic color-tunable LED having shaped recesses 18(1a), 18(1b), and 18(1c) of the same or different densities patterned in a first active doped layer 12 and capable of emitting visible light in multiple colors or a fixed color.

[0065] In other examples, the color-tunable LEDs may have additional components added to form the basis of pixel elements. These additional components may take the form of device elements, such as transistors, capacitors, and diodes, as exemplified. The device elements, together with the color-tunable LED system 10(1), may be electrically connected to form various circuits, such as current sources and active matrix circuits for each pixel element, as exemplified. The pixel elements function by rapidly switching between two or more emission wavelengths in response to a corresponding rapid change in drive current density, allowing the eye to perceive a single color. Individual pixel elements may be arranged multiple times to produce a full-color-tunable LED display system of any desired shape or resolution.

[0066] In an example where the color-tunable LED system 10(1) is included in the pixel elements, additional circuitry can be integrated to feed voltage and current signals to drive the LED array, and together they constitute an LED display system. The circuitry can be in the form of an external chip, or it can be integrated on a chip with the LEDs to create an optionally monolithic LED display system.

[0067] The color-tunable LED system 10(1) and color-tunable LED display system described and claimed herein offer numerous advantages and are effectively used in many different applications, such as microdisplays and larger format displays, commercial lighting, light-based data communications, etc. In particular, examples of this technology provide color-tunable LEDs that can emit light across the visible spectrum without requiring any additional color converters. This reduces complexity, provides better performance, and lowers costs for many applications.

[0068] Furthermore, in other examples, a single-color tunable LED system 10(1) can be configured to act as a pixel, i.e., a luminance center, either individually or in combination with neighboring subpixels, instead of using three LEDs to selectively emit red, green, and blue light, as is the common RGB approach widely used today. Reducing the number of LED subpixels used to form a pixel increases the potential display resolution and reduces the footprint. This smaller footprint is particularly advantageous in μ-LED displays intended for near-eye applications such as virtual reality or extended reality. It also reduces costs and enables more efficient manufacturing.

[0069] like Figure 6A As shown, a plurality of color-tunable light-emitting diode (LED) elements 610 can be arranged in an array 600 to form an image reconstruction and color reproduction electronic display according to one embodiment of the present application. Each LED can be tuned to emit a given color from a series of colors. This color tunability is achieved through current density, as explained more fully in US2022 / 0367754A1 application – and said application is incorporated herein in its entirety. For example, the first color 310 (refer to...) Figure 8A ) can be selected and in exemplary LED elements (such as Figure 6A The LED element 610 emits at point 610. This LED element 610 can then be tuned to a second (or more) color 320 over another time period. If this other color is switched back to the first color, and then quickly switched back to another color, the human visual system (HVS) perceives this as a combined color 330. This process is known in the art as field sequence color (FSC). In this embodiment, the first field 1 and the second field 2 alternate in a repetitive manner over time, such as... Figure 7 As illustrated, in several embodiments, the applied current can be set to a frequency greater than 48 Hz. This rate tends to correspond to the scintillation fusion frequency of the HVS.

[0070] The color of LED 610 is set by an electric current through the process taught in application US2022 / 0367754 A1. Brightness (i.e., the emitted energy) is set by the pulse width. This second process is referred to in the art as pulse width modulation. The combination of these two processes can be applied in novel ways to these LED displays disclosed herein and in the commonly owned application US2022 / 0367754A1. Since the time-mixing (FSC) color point 330 can be reproduced together with other emitted color points 340 and 350, a range of other color combinations exist, referred to in the art as metamerism. Figure 8AIn this context, the metamerism used for color point 330 refers to those colors located within the available range between the first color 310 and the second color 350 on one side of the color arc 300 for the emissive color 300, while the metamerism of those colors lies between the first color 320 and the second color 340 on the other side of the color arc 300. This means that theoretically, there are an infinite number of metamerism combinations for each color point 330. In practice, in a digital quantization system, there will be a finite number available, depending on the bit depth of the limiting function block.

[0071] A well-known problem in the field of FSC (Full Screen Display) is the phenomenon known as "color splitting," which typically manifests as "rainbow edges." Color splitting occurs when the viewer's gaze moves across the screen and the colors no longer blend together. Previous practitioners have sought various solutions. The most common approach is to increase the field rate. The drawback of this method is that power consumption increases with the rate. This paper discloses a most satisfactory method that leverages the novel features of this application in conjunction with a better understanding of HVS (High-Speed ​​Screen).

[0072] exist Figure 6B The image shows two colors, for example, from Figure 8A The first color 340 (at the first LED emitter) and the second color 350 (at the second LED emitter) are in a pattern. Figure 6A An array of LED emitters 600, wherein the two colors, when spatially mixed by HVS, result in a perceived color point 330. Furthermore (in another embodiment), it should be noted that the first LED emitter may emit a color point 340 in field 1. In the subsequent field 2, as... Figure 6C As shown, the same LED emitter 610 can emit color point 350. Therefore, at a single LED emitter 610, the LED operates in a field-order color (FSC) reproduction mode perceived by the HVS as color point 330. The combination of spatial mode (referred to in the art as spatial dithering) with the FSC sequence results in a novel chromatic spatiotemporal dithering mode that robustly solves the color splitting problem of individual FSCs.

[0073] It should be understood that not all colors possess a series of metamerisms. Some colors, namely those within a single emission wavelength / color range of 300 and those within the violet line of 360 (e.g., ...), are metamerisms. Figure 8B The magenta 365 shown has only one set of emitted colors that can be mixed together to reproduce the desired perceived color. Due to the curved nature of the color space range, those colors within a single emission wavelength range, as well as any two different emitted colors, reproduce the perceived color within the curved boundary. Therefore, the system uses the same color for both the field and the mode of spatiotemporal jitter; that is, jitter-free modes can be available (except for degenerate modes in a mathematical sense).

[0074] While most colors will have a range of available metamers, in a given instance, some metamer combinations may be more desirable. For example, in some instances, it might be desirable to use metamers with minimal perceived brightness difference, so that the spatiotemporal jitter pattern appears smooth and uniform in the luminance channels of the HVS. In some instances, given that the emitted color is controlled by current, it might be desirable to select metamer pairs using the least power. These different choices can be referred to as metamer strategies.

[0075] There exists a color line 370 that is to be reproduced substantially in the middle of the domain, which, when selecting metamerism pairs with substantially the same y-value, utilizes the property of equal brightness. For colors on either side, one emitted color will have to be brighter than the other, resulting in a difference in luminance. Among these colors, it is best to select metamerism pairs that are substantially equal in perceived luminance when the y-value is multiplied by the desired brightness. The resulting pairs will then have similar luminance, thereby reducing the chance of visible spatiotemporal artifacts.

[0076] exist Figure 9A The diagram shown is a top-level block diagram 900 of a possible embodiment of driving electronics for a display contemplated by this application. Conventionally, the display transmits color information per pixel as tristimulus gamma-quantized digital values ​​R*G*B*. These can be converted to linear RGB values ​​by a gamma conversion function block 910. This can be a simple lookup table (LUT), as detailed in US 8,411,022, which is incorporated herein by reference. This can be followed by a novel metamerism selection function block 920.

[0077] To simplify the selection of metamers and the calculation of luminance, RGB values ​​can be converted to any of several tristimulus values ​​known in the art, one of which is luminance (e.g., xyY) or a functional equivalent. The xy value is used to select unscaled metamer pairs and their relative luminance ratios. Taking into account the different inherent energies emitted by the LED at different emission wavelengths and the different currents used to control the emitted color, this relative luminance value is then further scaled according to the relative luminance used to provide the desired luminance value. After selecting the metamer pairs, only one emitted color is selected per field per pixel. Along with the emitted color value (i.e., the desired current) is the desired luminance value (i.e., the desired pulse width). Both of these values ​​can be in digital form.

[0078] In one implementation, it may be advantageous to select metamerism strategies and metamerism pair selections "offline" (i.e., using mathematical formulas in a computer or manually) for a selected set of colors to be reproduced. In online hardware, spatial color groups can be stored in a larger lookup table for direct use, or in a smaller lookup table (LUT) for interpolating metamerism pairs among the selected pre-computed metamerisms. This arrangement has the advantages of computational simplicity and makes the selection from the range of available metamerism pairs causally deterministic, rather than an ill-posed problem.

[0079] Figure 9A Advanced metamer selection block 920 in Figure 9C The input is linearized RGB data, which is converted and transformed into an xyY color space by a color space converter block 921 using methods well known in the art. The x and y values ​​are the color coordinates of the input color in the CIE 1931 color space 300, such as... Figure 8A and Figure 8B As shown. The Y value is the luminance of that color point.

[0080] The xy color point is used as an index to a metamerism lookup table (MLUT) block 922, which outputs the relative brightness of the metamerism color pair and the maximum luminance value (MaxY) that can be used for this color. The relative brightness of the metamerism pair defines the position of the color along the color line that the metamerism pair can reproduce. Considering that the color-tunable LED system 10(1) can have different light output efficiencies at different emitted colors, the relative brightness can also be encoded and compensated for this, so it is practical to select the metamerism pair and its associated relative brightness value offline and store it in the MLUT block 922. The third value to be stored and retrieved is the maximum luminance (MaxY) that can be used for the color at a given xy color point.

[0081] Brightness scaling block 923 can then use the ratio of the Y and MaxY of the colors to scale the relative brightness of the two colors in a metameris pair as follows:

[0082] Relative brightness X(Y / MaxY) = Brightness value

[0083] Color and brightness values ​​are passed to a spatiotemporal pattern generator block 924, which can select a centered color to emit given a field and pixel position. This could be... Figure 6B and Figure 6C The chessboard pattern, or some other pattern that is considered desirable in a specific instance of the implementation.

[0084] Color and brightness values ​​are transmitted to Figure 9AThe digital-to-analog converter 930 is shown. The color-tunable micro-light-emitting diode (μ-LED) array 940 receives and stores analog voltages to control the current and pulse width of each pixel.

[0085] exist Figure 9B The diagram shows an LED pixel element and its driver and control circuitry 945. It should be understood that this is merely a schematic diagram and those skilled in the art will be able to design functionally equivalent circuits in other ways. The pixel element and its driver and control circuitry 950 may be constructed by connecting a micro-LED 941 in series with an adjustable constant current supply element 942 and a power switch 943. The adjustable constant current supply element 942 may be controlled by a voltage stored in a sample-and-hold circuit 944 that receives the voltage value of the color value signal. The power switch 943 may be controlled by a comparator circuit element 946 that compares a stored pulse width modulation (PWM) value from a sample-and-hold circuit 947 with a pulse width modulation ramp from a pulse width ramp generator 950. The timing of the sample-and-hold circuit may be controlled by a common data scan signal, such as for an active matrix display backplane.

[0086] exist Figure 10 The image shows an array 1000 of μ-LEDs, which includes color-tunable μ-LED emitters 1010 in orthogonal mode and an array of lower-density fixed-color μ-LED emitters 1020. (Reference) Figure 10 And showing the CIE 1931 color chart Figure 8C The color-tunable μ-LED 1010 can be tuned along the 'yellow line' 390, essentially between a red 350 nm wavelength and a green 380 nm wavelength, while the fixed-color μ-LED 1020 can be essentially blue 320 nm. This layout is designed for HVS utilization along... Figure 8C The longer wavelengths shown on the right side of the CIE 1931 color chart are significantly optimized to provide high-resolution luminance information. It should be understood that when focusing on longer wavelengths, the very short wavelength of blue at approximately 950 nm is poorly sampled by the eye and becomes out of focus.

[0087] Of course, many other layouts may also be used and conceived within the scope of this application.

[0088] Figure 11 A high-level block diagram of a display system implementing an embodiment of this application is shown. Gamma-quantized R*G*B* tristimulus color values ​​can be input into a gamma-corrected lookup table (LUT) 910 to output linear RGB values. These values ​​are stored in an online buffer 1120 to provide data to a subpixel rendering (SPR) block 1125. The SPR block 1125 utilizes an SPR filter. The following filter kernels can be used to filter the blue plane values: 0.25 0.25 0.25 0.25

[0091] This filter provides an average of the blue values ​​mapped to the surrounding color-tunable μ-LED 1010, which cannot provide the full-color blue light expected, thus allowing the blue μ-LED 1020 to provide that light.

[0092] The red (R) and green (G) values ​​can be optionally modified by using the following filter kernels that sample the blue plane:

[0093] (Divide by 8 and scale according to blue luminance)

[0094] If the blue μ-LED subpixels have the same density (resolution) as the color-tunable μ-LEDs, then this value added to the red and green values ​​provides a means of reconstructing the high spatial frequency luminance contribution originally provided by the blue values.

[0095] The SPR R'G'B' data is passed to LUT 1130, which maps the data to values ​​utilized by a mixture of color-tunable and fixed μ-LEDs in μ-LED array 1140. The R / G color is the ratio of R' to G' from a given hue specified along the 'yellow line'. The R+G value is the desired luminance value as a percentage of pulse width modulation. This value considers not only the combined luminance of the red (R') and green (G') values ​​but is also adjusted based on the efficiency of the color-tunable μ-LED 1010 at each given R / G value. The B" value is the desired luminance value as a percentage of pulse width modulation; the B" value is also adjusted based on the efficiency of the blue μ-LED 520 at each given B" value. By using a LUT instead of the complex mathematical algorithms represented by the LUT, LUT 1130 can be programmed for different μ-LED arrays, thereby reducing manufacturing costs by using the same image processor design.

[0096] The digital value from LUT 1130 is passed to digital-to-analog (D / A) converter 1150, which provides the analog voltage used by driver 1140 of the μ-LED array.

[0097] The color-tunable μ-LED 1010 has the following characteristics: Figure 5B The driver circuit is shown and explained above. The fixed blue μ-LED 1020 can have a driver that omits the color value sampling and holding circuit and provides a fixed value constant current source.

[0098] exist Figure 12The image shows a top view of an array 1200 of μ-LEDs, which includes color-tunable μ-LED emitters 1210 in orthogonal mode and an array of fixed-color μ-LED emitters 1220 of the same density. (Reference) Figure 12 And showing the CIE 1931 color chart Figure 8C The color-tunable μ-LED 1210 can be tuned along the 'yellow line' 390 between a substantially red 350 wavelength and a green 380 wavelength, while the fixed-color μ-LED 1220 can be substantially blue 320. The system provides full-color reproduction and image reconstruction with two sub-pixels per pixel, where incoming pixels can be mapped to the color-tunable μ-LED and the adjacent fixed blue emitting μ-LED.

[0099] Figure 13 A high-level block diagram of a display system implementing an embodiment of this application is shown. Gamma-quantized R*G*B* tristimulus color values ​​are input to a LUT 1330, which maps the data to values ​​utilized by a mixture of color-tunable μ-LEDs and fixed-color μ-LEDs from a μ-LED array 1340. The R / G color is the ratio of R' to G' from a given hue specified along the 'yellow line'. The R+G value is the desired luminance value as a percentage of pulse width modulation. This value takes into account not only the luminance of the combined red (R) and green (G) values, but is also adjusted based on the efficiency of the color-tunable μ-LED 1210 at each given R / G value. The B” value is the desired luminance value as a percentage of pulse width modulation; the B” value is also adjusted based on the efficiency of the blue μ-LED 1220 at each given B” value. By using a LUT instead of the complex mathematical algorithms represented by the LUT, the LUT 1330 can be programmed for different μ-LED arrays, thereby reducing manufacturing costs by using the same image processor design.

[0100] The enumerated implementation schemes

[0101] The embodiments enumerated below are presented to illustrate certain aspects of this disclosure and are not intended to limit its scope. The use of the words “include,” “includes,” and / or “including” encompasses all the following meanings: “comprise,” “comprises,” “comprising,” “consisting of,” “substantially including,” etc.

[0102] The first enumerated embodiment includes: an LED system capable of emitting light with multiple peak wavelengths in response to changes in drive current density, the system comprising: one or more pixel elements, each of the one or more pixel elements including one or more LEDs, each of the one or more LEDs including: a first active doped layer located on a substrate and selectively patterned along a surface opposite to the substrate with recesses of one or more shapes and having one or more spacings to promote controlled color emission in an MQW layer of an MQW region; the MQW region formed on the surface of the first active doped layer, wherein each of the MQW layers is alloyed with a certain percentage of indium to promote the controlled color emission, wherein the portion of the MQW layer conforming to the recess has a lower concentration of alloyed percentage of indium compared to other portions of the MQW layer, wherein the alloyed percentage of indium decreases with distance from the portion of the MQW layer conforming to the recess; and a second active doped layer formed on the MQW region, having an opposite charge to the first active doped layer.

[0103] The second enumerated embodiment includes any one of the first enumerated embodiments, further comprising: a transition region located between each of the portions of the MQW layer conforming to the recess and each of the other portions of the MQW layer, and the transition region having a higher concentration of alloyed percentage of indium compared to the other portions of the MQW layer.

[0104] The third enumerated implementation includes any one of the first to second enumerated implementations, and further includes an electron blocking layer located between the MQW region and the second active doped layer.

[0105] The fourth enumerated embodiment includes any one of the first to third enumerated embodiments, and further includes: the recess having an inner surface at an angle between 0 degrees and 90 degrees relative to the substrate.

[0106] The fifth enumerated embodiment includes any one of the first to fourth enumerated embodiments, and further includes: the recess having an inner surface at an angle between 90 degrees and 180 degrees relative to the substrate.

[0107] The sixth enumerated embodiment includes any one of the first to fifth enumerated embodiments, and further includes: the recesses are spaced apart from each other at a distance between 150 nm and 10 μm.

[0108] The seventh enumerated implementation scheme includes any one of the first enumerated implementation schemes through the sixth enumerated implementation scheme, and further includes: the depth difference between each of the recesses is less than about 5 μm.

[0109] The eighth enumerated implementation includes any one of the first to seventh enumerated implementations, and further includes: the shape of the outer periphery of the recess includes one or more circles, triangles, squares, pentagons or hexagons.

[0110] The ninth enumerated implementation includes any one of the first to eighth enumerated implementations, and further includes: the LED system is formed entirely of a common single material system.

[0111] The tenth enumerated embodiment includes any one of the first to ninth enumerated embodiments, and further includes: one or more driving circuit system elements coupled to each of the one or more pixel elements.

[0112] The eleventh enumerated embodiment includes any one (or excludes) of the first through tenth enumerated embodiments, and further includes: a method for fabricating an LED system capable of emitting light of multiple peak wavelengths in response to a change in drive current density, the method comprising: forming one or more pixel elements, each of the one or more pixel elements including one or more LEDs, wherein the forming further comprises: providing a first active doped layer on a substrate; selectively patterning the first active doped layer along a surface opposite to the substrate with recesses of one or more shapes and having one or more spacing configurations. The MQW region is formed on one surface of the first active doped layer to promote controlled color emission in the MQW layer of the MQW region; the MQW region is formed on each of the MQW layers with a certain percentage of indium alloyed to promote the controlled color emission, wherein the portion of the MQW layer conforming to the recess has a lower concentration of alloyed percentage of indium compared to other portions of the MQW layer, wherein the alloyed percentage of indium decreases with distance from the portion of the MQW layer conforming to the recess; and a second active doped layer is formed on the MQW region, the second active doped layer having an opposite charge to the first active doped layer.

[0113] The twelfth enumerated embodiment includes any one of the first to eleventh enumerated embodiments (or none of them), and further includes providing a transition region between each of the portions of the MQW layer that conform to the recess and each of the other portions of the MQW layer, and the transition region having a higher concentration of alloyed percentage of indium compared to the other portions of the MQW layer.

[0114] The thirteenth enumerated implementation includes any one of the first enumerated implementations to the twelfth enumerated implementations (or excludes any one of them), and further includes: forming an electron blocking layer between the MQW region and the second active doped layer.

[0115] The thirteenth enumerated embodiment includes any one of the first to twelfth enumerated embodiments (or excludes any one of them), and further includes: the recess having an inner surface at an angle between 0 degrees and 90 degrees relative to the substrate.

[0116] The fourteenth enumerated embodiment includes any one of the first to thirteenth enumerated embodiments (or excludes any one of them), and further includes: the recess having an inner surface at an angle between 90 degrees and 180 degrees relative to the substrate.

[0117] The fifteenth enumerated embodiment includes any one of the first to fourteenth enumerated embodiments (or excludes any one of them), and further includes: the recesses are spaced apart from each other at a distance between 150 nm and 10 μm.

[0118] The sixteenth enumerated implementation includes any one of the first enumerated implementations to the fifteenth enumerated implementation (or excludes any one of them), and further includes: the depth difference between each of the recesses is less than about 5 μm.

[0119] The seventeenth enumerated implementation includes any one of the first to sixteenth enumerated implementations (or excludes any one of them), and further includes: the shape of the outer periphery of the recess includes one or more circles, triangles, squares, pentagons or hexagons.

[0120] The eighteenth enumerated implementation includes any one of the first to seventeenth enumerated implementations (or none of them), and further includes: the LED system is formed entirely of a common single material system.

[0121] The nineteenth enumerated embodiment includes any one of the first enumerated embodiments through the eighteenth enumerated embodiments (or excludes any one of them), and further includes: forming one or more driving circuit system elements coupled to each of the one or more pixel elements.

[0122] The twentieth enumerated embodiment includes any one of the first to nineteenth enumerated embodiments (or excludes any one of them), and further includes: a method for controlling one or more colored emissions, the method comprising: providing an LED system including a first active doped layer, an MQW region, and a second active doped layer; wherein the first active doped layer is selectively patterned along a surface opposite to a substrate with recesses of one or more shapes and having one or more spacing configurations to facilitate controlled color emission in the MQW layer of the MQW region; wherein the MQW region is formed on the first active doped layer. Above the surface of the source doped layer, each of the MQW layers is alloyed with a certain percentage of indium to promote the controlled color emission, wherein the portion of the MQW layer conforming to the recess has a lower concentration of alloyed indium percentage compared to other portions of the MQW layer, wherein the alloyed indium percentage decreases with distance from the portion of the MQW layer conforming to the recess; and wherein the second active doped layer is formed on the MQW region, having the opposite charge to the first active doped layer; and the application of current to the LED system is changed over time to alter the one or more color emissions.

[0123] The twenty-first enumerated implementation includes any one of the first to twenty enumerated implementations (or none of them), and further includes: the application of the change of current over time further includes: changing the duty cycle and current level of each emission wavelength.

[0124] The twenty-second enumerated implementation includes any one of the first enumerated implementations to the twenty-first enumerated implementation (or none of them), and further includes: the application of the current that changes over time has a frequency greater than 48 Hz.

[0125] The twenty-third enumerated implementation includes any one of the first enumerated implementations to the twenty-second enumerated implementations (or none of them), and further includes: the application of the time-varying current further includes: mixing two or more wavelengths, each having a unique current level and duty cycle, within a single cycle.

[0126] The twenty-fourth enumerated embodiment includes any one (or none) of the first to twenty-third enumerated embodiments, and further includes: an LED system capable of emitting light of multiple peak wavelengths in response to changes in driving current density, the system including: one or more pixel elements, each of the one or more pixel elements including one or more LEDs, each of the one or more LEDs including: a first active doped layer, the first active doped layer being located on a substrate and selectively patterned along a surface opposite to the substrate with recesses of one or more shapes and having one or more spacing arrangements to facilitate... Controlled color emission in an MQW layer within an MQW region; the MQW region being formed on one surface of the first active doped layer, wherein each of the MQW layers is alloyed with an independent percentage of indium to promote the controlled color emission, wherein the portion of the MQW layer conforming to the recess has a lower concentration of alloyed percentage of indium compared to other portions of the MQW layer, wherein the alloyed percentage of indium decreases with distance from the portion of the MQW layer conforming to the recess; and a second active doped layer formed on the MQW region, having an opposite charge to the first active doped layer.

[0127] The twenty-fifth enumerated implementation includes any one of the first to twenty-fourth enumerated implementations (or excludes any one of them), and further includes: an electron blocking layer located between the MQW region and the second active doped layer.

[0128] The twenty-sixth enumerated embodiment includes any one of the first to twenty-fifth enumerated embodiments (or none of them), and further includes: a method for controlling a μ-LED display, the μ-LED display including a plurality of LED elements, each LED element including a plurality of MQW regions, wherein each such MQW region is selectively doped to emit a desired color wavelength and such that each LED element emits a perceived single color wavelength, the perceived single color wavelength being a composite color of the desired color wavelength of each MQW region, the method comprising: driving a first LED element in a first time period to emit a first color in a first field; and driving the first LED element in a second time period to emit a second color in a second field to influence a perceived composite field-sequential color including the first color and the second color.

[0129] The twenty-seventh enumerated implementation includes any one of the first enumerated implementations to the twenty-sixth enumerated implementations (or none of them), and further includes: the first color of the first field and the second color of the second field forming a first metamerism for the perceived single color wavelength.

[0130] The twenty-eighth enumerated embodiment includes any one of the first enumerated embodiments to the twenty-seventh enumerated embodiments (or none of them), and further includes: a second LED element adjacent to the first LED element is driven in the first field to emit the second color, and driven in the second field to emit the first color.

[0131] The twenty-ninth enumerated implementation includes any one of the first enumerated implementations to the twenty-eighth enumerated implementations (or excludes any one of them), and further includes: the μ-LED display is affecting spatial jitter.

[0132] The thirtieth enumerated implementation includes any one of the first to twenty-ninth enumerated implementations (or none of them), and further includes: the μ-LED display positively influences the field sequence color sequence.

[0133] The thirty-first enumerated embodiment includes any one of the first enumerated embodiments to the thirty-first enumerated embodiments (or excludes any one of them), and further includes: the first LED element is driven in a third time period to emit a third color in a third field, and the first LED element is driven in a fourth time period to emit a fourth color in a fourth field, such that the third color and the fourth color are perceived as the same color as the first metamerism.

[0134] The thirty-second enumerated implementation scheme includes any one of the implementation schemes from the first enumerated scheme to the thirty-first enumerated scheme (or none of them), and further includes: the desired perceived color can be rendered by a series of metamerisms that can be selected from a set of first colors and a set of second colors.

[0135] The thirty-third enumerated implementation includes any one of the first enumerated implementations to the thirty-second enumerated implementation (or none of them), and further includes: the metamer selected to render the desired perceived color includes metamers having minimal perceived brightness differences.

[0136] The thirty-fourth enumerated implementation includes any one of the first to thirty-third enumerated implementations (or none of them), and further includes: the metamer selected to render the desired perceived color includes a metamer with the least power.

[0137] The thirty-fifth enumerated embodiment includes any one of the first to thirty-fourth enumerated embodiments (or excludes any one of them), and further includes: a μ-LED display comprising a plurality of LED elements, each LED element comprising a plurality of MQW regions, wherein each such MQW region is selectively doped to emit a desired color wavelength and such that each LED element emits a perceived single color wavelength, the perceived single color wavelength being a composite color of the desired color wavelength of each MQW region; the μ-LED display further includes: a metamerism selection block, the metamerism selection block receiving image input data indicating a desired color and a desired brightness to be rendered; the metamerism selection block calculating metamerism selection and brightness to be rendered by the LED element and at least one neighboring LED element, such that the LED element and the at least one neighboring LED element render the desired color and the desired brightness in a spatiotemporal scheme.

[0138] The thirty-sixth enumerated embodiment includes any one of the first to thirty-fifth enumerated embodiments (or none of them), and further includes: wherein the LED element and at least one adjacent LED element respectively render a first color and a second color, the first color and the second color forming a metamerism for the desired color to be rendered.

[0139] The thirty-seventh enumerated embodiment includes any one of the first to thirty-six enumerated embodiments (or none of them), and further includes: the LED element and the at least one adjacent LED element being assigned relative brightness values ​​to render the desired brightness.

[0140] The thirty-seventh enumerated implementation scheme includes any one of the first enumerated implementation schemes to the thirty-sixth enumerated implementation schemes (or excludes any one of them), and further includes: the metamer selection block further includes a pre-calculated metamer lookup table.

[0141] The thirty-eighth enumerated implementation scheme includes any one of the implementation schemes from the first enumerated to the thirty-seventh enumerated (or excludes any one of them), and further includes: the metamer selection block further includes a spatiotemporal mode generator block.

[0142] The thirty-ninth enumerated implementation includes any one of the first to thirty-eighth enumerated implementations (or none of them), and further includes: the spatiotemporal pattern generator block selects the color and brightness of each LED element according to the LED pattern constituting the μ-LED display.

[0143] The fortieth enumerated implementation includes any one of the first enumerated implementations to the thirty-ninth enumerated implementation (or excludes any one of them), and further includes: the LED pattern includes one of the group: an array of LED elements, a checkerboard pattern of LED patterns.

[0144] The forty-first enumerated implementation includes any one of the first enumerated implementations to the fortyth enumerated implementation (or excludes any one of them), and further includes: the μ-LED display further includes a subpixel rendering (SPR) block.

[0145] The forty-second enumerated implementation includes any one of the first enumerated implementations to the forty-first enumerated implementation (or excludes any one of them), and further includes: the SPR block includes a plurality of SPR filters, the SPR filters including kernels that affect the rendering of sub-pixels to neighboring LED elements.

[0146] Having thus described the basic concept of the present technology, it will be quite apparent to those skilled in the art that the foregoing detailed disclosure is intended only by way of example and is not intended to be limiting. Although not explicitly stated herein, various changes, modifications, and alterations will occur and be contemplated by those skilled in the art. These changes, modifications, and alterations are intended to be made hereby and are within the spirit and scope of the present technology. Furthermore, the listed order of processing elements or sequences, or the use of numbers, letters, or other names, is therefore not intended to limit the scope of this application.

Claims

1. A method for controlling a μ-LED display, the μ-LED display comprising a plurality of LED elements, each LED element comprising a plurality of MQW regions, wherein each such MQW region is capable of selectively emitting one or more desired color wavelengths and such that each LED element emits a perceived single color wavelength that is a composite color of the desired color wavelengths of each MQW region, the method comprising: driving a first LED element in a first time period to emit a first color in a first field; driving the first LED element in a second time period to emit a second color in a second field to affect a perceived composite field sequential color that includes the first color and the second color.

2. The method of claim 1, wherein the first color of the first field and the second color of the second field form a first metamer for the perceived single color wavelength.

3. The method of claim 2, wherein a second LED element adjacent to the first LED element is driven to emit the second color in the first field and to emit the first color in the second field.

4. The method of claim 3, wherein the μ-LED display is affecting spatial dithering.

5. The method of claim 4, wherein the μ-LED display is affecting a sequence of field sequential colors.

6. The method of claim 2, wherein the first LED element is driven in a third time period to emit a third color in a third field and the first LED element is driven in a fourth time period to emit a fourth color in a fourth field such that the third color and the fourth color are perceived as the same color as the first metamer.

7. The method of claim 2, wherein a desired perceived color is capable of being rendered by a range of metamers capable of being selected from a set of first colors and a set of second colors.

8. The method of claim 7, wherein the metamer selected to render the desired perceived color includes a metamer having a minimum perceived luminance difference.

9. The method of claim 7, wherein the metamer selected to render the desired perceived color includes a metamer having a minimum power.

10. A μ-LED display, the μ-LED display comprising a plurality of LED elements, each LED element comprising a plurality of MQW regions, wherein each such MQW region is selectively doped to emit a desired color wavelength and such that each LED element emits a perceived single color wavelength that is a composite color of the desired color wavelengths of each MQW region, the μ-LED display further comprising: a metamer selection block, the metamer selection block receiving image input data, the image input data indicating a desired color and a desired luminance to render; a field sequential color generator, the field sequential color generator driving the plurality of LED elements to emit the desired color in a first field and the desired luminance in a second field. The metamer selection block calculates a metamer selection and a brightness to be rendered by the LED element and at least one neighboring LED element, such that the LED element and the at least one neighboring LED element render the desired color and the desired brightness in a spatio-temporal scheme.

11. The p-LED display of claim 10, wherein the LED element and at least one neighboring LED element render a first color and a second color, respectively, the first color and the second color forming a metamer for the desired color to be rendered.

12. The p-LED display of claim 11, wherein the LED element and the at least one neighboring LED element are assigned relative brightness values to render the desired brightness.

13. The p-LED display of claim 12, wherein the metamer selection block further comprises a look-up table of pre-computed metamers.

14. The p-LED display of claim 13, wherein the metamer selection block further comprises a spatio-temporal pattern generator block.

15. The p-LED display of claim 14, wherein the spatio-temporal pattern generator block selects the color and brightness of each LED element according to a pattern of LEDs constituting the p-LED display.

16. The p-LED display of claim 14, wherein the LED pattern comprises one of a group, the group comprising: a grid of LED elements, a pattern of LEDs.

17. The p-LED display of claim 16, wherein the p-LED display further comprises a sub-pixel rendering (SPR) block.

18. The p-LED display of claim 17, wherein the SPR block comprises a plurality of SPR filters, the SPR filters comprising kernels affecting sub-pixel rendering to neighboring LED elements.

Images